preparation | The synthesis method of indazole compounds mainly uses O-halophenylcarbonyl compounds as raw materials to generate phenylhydrazine (or phenylhydrazone) then, intramolecular cyclization, diazotization reaction of O-methylaniline compounds, diazotization reaction of Isatin, and diazotization reaction of indole, etc. However, the above synthetic methods are low in yield, complicated in post-treatment, and are not suitable for mass production of indazole. 6-bromo-1h-indazole-4-carboxylic acid, as a basic raw material in pharmaceutical chemistry, is cheap and easily available, and can be further synthesized to obtain valuable pharmaceutical intermediates. In this paper, 1H-indazole -4-carboxylic acid as raw material, the introduction of bromine atom in indazole benzene ring 6, synthesis of 6-bromo-1h-indazole-4-carboxylic acid. The synthesis reaction formula is shown below: 6-bromo-1h-indazole-4-carboxylic acid synthesis reaction formula at room temperature, the starting material 1H-indazole-4-carboxylic acid is dissolved in a three-neck reaction flask with anhydrous acetic acid, the system is heated and stirred, after the substrate is dissolved and clarified, the liquid bromine is dissolved in anhydrous acetic acid, and slowly added dropwise; in the case of an oil bath at 90 ° C., the reaction was refluxed by condensation for 14 hours. The progress of the reaction was checked by thin layer chromatography, and heating was stopped after the reaction was complete. The system appeared turbid, resulting in a white precipitate, which was cooled in an ice bath, vacuum filtered, and the solid was washed with ethyl acetate first, and then washed with diethyl ether to obtain 6-bromo-1h-indazole-4-carboxylic acid. |